Untersuchungen zur Rolle des Natrium-Stoffwechels im Zellkern der Rattenleber

Siebert, Günther; Langendorf, H.; Hannover, Rosemarie; Nitz-Litzow, D; Pressman, Berton C.; Moore, Charlotte E.

doi:10.1515/bchm2.1966.343.1.101

Cited by 31 publications

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“…With electron microprobe analysis, maturating chick red blood cells (18 day, near hatching) had N͞C ratios ϭ 0. 48 (44); for rat renal tubular cells, the N͞C ratios for Cl Ϫ and Na ϩ varied somewhat depending on the cytoplasmic region analyzed (45,46); and in rat hepatocytes, where N͞C ϭ 0.9 for Cl Ϫ and 1.1 for Na ϩ (47). It is evident that in all of these studies, there are only small variations in N͞C values for Cl Ϫ and Na ϩ .…”

Section: CLmentioning

confidence: 82%

Fluorescent imaging of Cl ^- in Amphiuma red blood cells: How the nuclear exclusion of Cl ^- affects the plasma membrane potential

Hoffman

Geibel²

2005

Proc. Natl. Acad. Sci. U.S.A.

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In this work, we test the idea that most, if not all, cellular Cl ؊ of Amphiuma red blood cells is contained in the cytoplasm. If true, this could resolve the difference between the measured plasma membrane potential (E m) and that expected from the Donnan equilibrium distribution of Cl ؊ . We studied the changes in the fluorescence intensity of the Cl ؊ -sensitive dye, MQAE, entrapped in red cells that occurred when intracellular Cl ؊ was exchanged with NO 3 ؊ . We could thus monitor the distribution of Cl ؊ between the nuclear and cytoplasmic compartments. We found that essentially all of the cell's Cl ؊ resides in the cytoplasm. Knowing the volume of the cell occupied by the nucleus, we could accordingly correct the measured values of cell Cl ؊ . This resulted in establishing a concordance between the measured values of E m and those calculated from the corrected values of the Cl ؊ ratio, thus explaining the discrepancy. The exclusion of Cl ؊ from the nucleus may result from its unusually high content of ''excess'' DNA that imposes an imbalance of net negative charge.MQAE ͉ nuclear͞cytoplasmic ratios T he equilibrium distribution of permeable ions such as Cl Ϫ across the plasma membrane of red blood cells should be determined by the membrane potential (E m ) that is set by the relative permeability to Na ϩ and K ϩ and their concentration gradients. This paper addresses the E m of Amphiuma red blood cells and the reason why the measured E m appears to differ significantly from that expected from the equilibrium distribution of Cl Ϫ . The idea that the E m of red blood cells in general and of human red cells in particular could be described by a Donnan potential is based on analyses (1-4) of the passive equilibrium distribution of permeable ions between the cytoplasm (Cl i Ϫ ) and the external medium (Cl o ). The E m of human red cells, measured indirectly with the use of fluorescent dyes (5), was found to vary quantitatively with the Donnan ratio of Cl i ͞Cl o (r Cl ). This was so when r Cl was varied either by changes in external pH (pH o ) (5-7) or by altering the concentration of Cl o by substitution with an impermeable anion (5). Validation that the fluorescence technique provided an accurate assessment of E m in human red cells stemmed from the concordance of E m determined directly in Amphiuma red blood cells by impalement with microelectrodes (8, 9, †) with those determined by the use of fluorescent dyes (5). These results established the basis for expecting measurements of E m in Amphiuma red blood cells to conform to a Donnan potential. However, analyses showed that, although the E m of Amphiuma responded to changes in Cl i produced by changes in pH o , the calculated values of E m based on measured values of Cl i and Cl o were significantly higher than the observed E m values. E m was calculated by use of the Nernst equation, E m ϭ 58 log Cl i ͞Cl o , where 58 is the value of RT͞F at 20°C., with R being the gas constant, T the temperature, and F, the Faraday constant. It turns out that the problem li...

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Section: CLmentioning

confidence: 82%

Fluorescent imaging of Cl ^- in Amphiuma red blood cells: How the nuclear exclusion of Cl ^- affects the plasma membrane potential

Hoffman

Geibel²

2005

Proc. Natl. Acad. Sci. U.S.A.

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“…It is not known to what extent the RPU'A polymerase attached to the chromatin is actually active in the cell. It should be mentioned, however, that the high ionic strength a t which optimal RNA synthesis occurs in the in vitro system may come close to the salt concentration in the nucleus of the living cell [33].…”

Section: Discussionmentioning

confidence: 99%

On the Synthesis of RNA in Lymphocytes Stimulated by Phytohemagglutinin

Hausen

Stein

Peters

1969

European Journal of Biochemistry

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The experimental conditions to study lymphocyte transformation in cultures derived from bovine lymph nodes are described. Both deoxyribonucleoprotein-bound and soluble RNA polymerase can conveniently be tested in cell lysates. During the course of transformation the activities of the two enzymes begin to rise a t the same time when the cells begin to accumulate stable RNA. At 30 h after addition of phytohemagglutinin both enzyme activities are enhanced by a factor of two over the controls.The transformation of small lymphocytes to large pyroninophilic cells under tho stimulus of phytohemagglutinin provides an excellent model system to study the conversion of resting cells to actively growing cells. The assumption that the synthesis of RNA may play a key role in this process has focused attention on the RNA metabolism in transforming lymphocytes [ 1 -81. A drastic increase in the incorporation of radioactive uridine into RNA soon after the addition of the stimulating agent phytoheniagglutinin indicated a rapid induction of RNA synthesis. The interpretation of these labelling experiments is difficult since the uptake of the labeled precursor into the intracellular nucleotide pool is increased considerably in lymphocytes treated with phytohemagglutinin [9,10]. Therefore it was decided to investigate the RNA synthesizing capacity of cell free systems derived from transforming lymphocytes. This approach avoids the discussion of "pool quesstions" and might give information as to what extent the RNA synthesizing apparatus of the cell is changed after stimulation.Different methods for studying RNA synthesis in cell free systems derived from animal cells have been described. Using bacterial RNA polymerase isolated chromatin has a template activity which changes with the physiological state of the cell [ll]. At low salt concentration isolated nuclei show RNA synthesizing activity which possibly reflects the activity of ribosomal operons within the nucleolus [12-151. The activity of cellular RNA polymerase bound to the chromatin can be tested at high salt concentration [16,17]. Finally, a soluble enzyme which uses exogeneous DNA as template for RNA synthesis can be extracted from the cells [is--211. The activities observed in these different assay systems probably reflect different aspects of tbe i n vivo conditions. Studies on the activity of chromatin-bound and of the soluble RNA polymerase will be described in this communication.I n order to perform such experiments large amounts of lymphocytes are needed. The limited supply of human blood used earlier [lo] prompted the investigation of other sources for lymphocytes. Bovine lymph node cells were found to respond to phytohemagglutinin in a similar way as human blood lymphocytes. These cells have been used throughout the studies. Culture conditions and the changes in leucine and uridine labelling as well as the net synthesis of DNA, RNA and protein after phytohemagglutinin stimulation will be described in the first section of this communication.Lymphocytes are particular...

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“…The nucleus of a variety of cells appears to contain considerably higher levels of Na+ than the cytoplasm (1)(2)(3)(4)(5)(6)(7)(8)(9). This nuclear Na+ does not equilibrate freely with that in the cytoplasm and does not seem to be maintained by an energy-requiring process (5). Cells and tissues reported to have a high nuclear Na+ concentration include amphibian oocytes (1, 2), liver (3-5), kidney (3,6,7), thymus (3), frog skin (6), and Ehrlich ascites cells (9).…”

mentioning

confidence: 99%

A possible mechanism for concentrating sodium and potassium in the cell nucleus

Moore¹,

Morrill²

1976

Biophysical Journal

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Untersuchungen zur Rolle des Natrium-Stoffwechels im Zellkern der Rattenleber

Cited by 31 publications

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Fluorescent imaging of Cl ^- in Amphiuma red blood cells: How the nuclear exclusion of Cl ^- affects the plasma membrane potential

Fluorescent imaging of Cl ^- in Amphiuma red blood cells: How the nuclear exclusion of Cl ^- affects the plasma membrane potential

On the Synthesis of RNA in Lymphocytes Stimulated by Phytohemagglutinin

A possible mechanism for concentrating sodium and potassium in the cell nucleus

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Untersuchungen zur Rolle des Natrium-Stoffwechels im Zellkern der Rattenleber

Cited by 31 publications

References 0 publications

Fluorescent imaging of Cl - in Amphiuma red blood cells: How the nuclear exclusion of Cl - affects the plasma membrane potential

Fluorescent imaging of Cl - in Amphiuma red blood cells: How the nuclear exclusion of Cl - affects the plasma membrane potential

On the Synthesis of RNA in Lymphocytes Stimulated by Phytohemagglutinin

A possible mechanism for concentrating sodium and potassium in the cell nucleus

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Product

Resources

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Fluorescent imaging of Cl ^- in Amphiuma red blood cells: How the nuclear exclusion of Cl ^- affects the plasma membrane potential

Fluorescent imaging of Cl ^- in Amphiuma red blood cells: How the nuclear exclusion of Cl ^- affects the plasma membrane potential